Forming method and apparatus



March 21, 1944. Q H, JR 2,344,743

' FORMING METHOD AND APPARATUS I Filed May 6, 1941 3 Sheets-Sheet 1' /NVE N TOR/ HENRY COLL/ER 544/ TH, JR.

Y HA RR/J, K/ECH, F0: TER a HARR/J March 1944- H. c. SMITH, JR

FORMING METHOD AND APPARATUS Filed May 6, 1941 3 Sheets-Sheet 5/NVENTO&/ HENRY C04 L/ER SM/ TH, JR.

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H 6 6 A &6 E w h" M E w v a m m 6 a HA RR/J K75: lllllll e FOR TH FIRMg7 TORLVE K5 Patented Mar. 21, 1944 UNITED STATES PATENT OFFICE FORMINGMETHOD AND APPARATUS Henry Collier Smith, In, Los Angeles, Calif.Application May a, 1941, Serial No. 392,082

21: Claims. (01. 113-44) My invention relates to procedures for formingobjects such as sheet metal blanks, with special reference todeformation by application of pressure, and is directed to a novelforming method adapted to be carried out by a novel forming means.

While the principles of the invention are applicable broadly to problemsof forming various types of blanks to desired configurations in variousfields of industry, the invention is being initially embodied in adrawing press for shaping sheet metal parts for aircraft and the like.For the purpose of the present disclosure, I elect to describe such anembodiment of the invention, but those skilled in the art will findadequate guidance therein for applying the invention wherever it mayhave utility.

The general object of the invention is to pro vide an efilcient andrelatively inexpensive forming apparatus that is exceptionally flexiblein operation and that offers a heretofore unattainable range ofdeformation in one shaping procedure. My invention involves theemployment of fiowable means under pressure to force a blank intointimate contact with a die or forming surface to cause the blank totake the configuration of the die. It is old in the art to provide abody of rubber or other deformable material in a confined space, toplace a blank against the deformable body, and to advance a forming dieagainst the blank into the confined space for the purpose of placing thedeformable body under su1'-,

ficient pressure to force the blank into intimate contact with theforming die. While this older practice has utility and can meet certainforming tasks satisfactorily, it does have definite limitations andinherent disadvantages that curtail its range of usefulness. It is anobject of the .present invention to provide a novel procedure that islargely free of such limitations and consequently is more efflcient andhas a wider range of application.

Some of the limitations and disadvantages of the older practicementioned above are attributable to the fact that the deformable meansemployed in the older combination is a coherent body nitude of pressure.The fact that a coherent body is employed also makes it impossible tovary the mass of the fiowable material in the confined space in thecourse oi a forming procedure. As for the engendering of pressure solelythrough the medium of the die, the fact that the pressure is a functionof the die movement more often than not precludes the attainment of anoptimum pressure at a desired stage in a die movement and only rarelypermits the application of optimum pressures at two diil'erent stages ofthe die movement.

In contrast, an object of my invention is to provide in such acombination a flowable means of substantially perfect fluidity forefflcient pressure distribution in all directions, and a further objectis to provide for close control of the pressure of the fiowable means incompleteindependence of die movement, in complete independence ofchanges in the effective volume of the confined space, and without thenecessity of uncovering the confined space or even interrupting anoperation cycle. It is my purpose to provide sufliciently close controlof both the die movement and the forming pressure to attain exceptionalflexibility in the sense of adaptability to a wide range of divergentforming procedures. The end sought is to permit the die maker and thepress operator to seek an ideal forming procedure for a given taskwithout compromising to any material degree because of the limitationsof the available apparatus.

One of the objects of my invention is to provide for intermittentlyprogressive formation of that is fluid in character only to a limiteddegree, and other shortcomings are attributable to the fact thatpressure in the deformable body is derived solely from the die and istherefore dependent upon movement of the die. The imperfect fluidity ofthe deformable body prevents uniform distribution of the engenderedpressure in all directions and precludes close, control of the pressureor even ascertainment of the maga blank with one set-up of the apparatusand in a single cycle of operations on the part of the apparatus. Ipropose to shape a blank by definite stages through a progressive seriesof configurations to a final predetermined configuration withoutchanging dies and without losing time between stages in the formingcycle. By resorting to stepby-step shaping to avoid overstressing themat'erial being shaped, I attain an exceptional range of deformationwithout breakage, and by covering the successive stages in a singlecycle or Operations I achieve new production economies. In this regardan object in mind is to provid for alternate forming operations in sucha cycle, for example, forming pressure on one portion of a blankalternating with forming pressure on another portion of the blank or,for another example, a drawing operation alternating with astraightening or flattening operation.

A further object of the invention relates to the attainment ofexceptionally deep draws by a male die. I propose to press the sheetmaterial against the advancin male die with such high pressure and suchuniformly distributed pressure: 'as to make the progressively contactingportion of the sheet in 'eifect integral with .the die. thereby avoidingslippage relative to the die with consequent stretching and rupture 'ofthe sheet material. For the attainment of deep drawing. I tur therpropose to provide for intermittently pressing out wrinkles and ridgesin the undrawn por tions of the sheet material.

Broadly described, the invention is characterized by the combination ofmeans providing a forming surface and flowable means including a body offluid to press a blank into intimate contact with the forming surface.The preferred form of the invention is characterized by the concept ofemploying a flexible wall or diaphra m of flowable material for thepurpose of separating the fluid from the blank and for the purpose oftransmitting pressure from the fluid bod to the blank.

One object of the invention is to provide flexible control means forclosely regulating the pressure of the fluid body preferably incooperation with similar means for varying the configur ion of, theforming surface. In one practice of the invention it is contem latedthat the configuration cf the forming-surface will be variablycontrolled by pressure opposing the pressure of the fluid body, and itis proposed to control the forming operation by varying the relativevalues of these two pressures. Thus it is contemplated that anintermittently progressive forming operas tion may be caused byfluctuating either the die pressure or the opposed pressure of the fluidbody. With reference 'to control, a further obliect of the invention isto provide an arrangement that is peculiarly suited for automaticoperation throughout a forming cycle.

Certain practices of the invention include the employment of a floatingforming member interposed between the blank and the diaphragm thatbounds the fluid body, and certain objects of the invention, which willbe understood later, relate to the design and function of such afloating member.

A still further object of the invention. is to provide a structure withindependently movable telescoped outer and inner rams without any gapsin effective cross-sectional areas.

Other objects and advantages of my invention will be apparent in themore detailed description to follow, taken with the accompanyingdrawings.

In the drawings. which are to be taken as illustrative only:

Figs. 1 to 7 are diagrammatic views representing successive stages in aforming procedure that may be followed in the practice of my invention;

Figs. 8 and 9 are diagrammatic views representing two stages in a secondforming procedure that may be followed;

Figs. 10 and 11 are diagrammatic views reprepractice of the invention;

Fig. 16 is a section taken as indicated by the irregular line |3|8 ofFig. 15: and

Fig. 17 is a simplifled verticaltsection of the apparatus combined witha diagram of a fluid-control system for the apparatus.

Fig. 1 represents an apparatus comprising an upper assembly generallydesignated 20 and a lower assembly generally designated 2| which areadapted to be brought together as shown in Fig. 2

to form a closed space or chamber 22. It is contemplated that one of thetwo assemblies 20 and 2| will present forming surfaces on one side of ablank 23 and that the other assembly will harbor a fluid body on theother side of the blank. In the particular. arrangement shown, the upperassembly includes an inner forming member 25 and an outer forming member26 that cooperate in defining a forming configuration. at least one ofthe two forming members being movable to permit the operator to vary theforming configuration. The inner forming member 25 which may be termedthe inner die has, for example, a forming recess 21 and a cutting recess28 while the outer forming member which may be termed the outer die hasa flat forming face 30 that is annular in plan.

The lower assembly 2| may include the following elements: an open topfluid receptacle 3| having a fluid passage 32; a fluid body 33 in thereceptacle, which fluid body may be either gaseous or liquid, but in thepreferred form of my invention is a body of oil; a suitable diaphragm 35spanning the fluid receptacle, which diaphragm may comprise a sheet ofrubber or like material; a clamping ring 35 engaging the'margin of thediaphragm; and a guide ring 31 that is in effect an extension of thereceptacle 3|.

In the particular practice of the invention representedby Figs. 1-7, athird forming member 38, which may be termed a floating forming memberor floating die, rests upon the diaphragm 35 within the guide ring 31.This floating forming member 38 may be in the form of a ring of taperedcross-sectional configuration as indicated in the drawings.

In preparation for the forming procedure represented by Figs. 1 to 7,the upper and lower assemblies 20 and 2| are spaced apart for access tothe chamber 22, and the blank 23 that is to be processed is placed inthe chamber on top of the floating die 38. The body of oil 33 is, ofcourse, at substantially atmospheric pressure and may be at a relativelylow level.

The next step is to bring the two assemblies 20 and 2| together tocompletely enclose the blank 23 as shown in Fig. 2. While the twoassemblies 20 and 2| are being brought together, the inner die 25 may bemaintained at a constant spatial relationship to the outer die 26 todeflne a desired initial configuration for the blank 23. In thepreferred practice of my invention, however, the two dies 25 and 26 ofthe upper assembly are independently movable toward the lower assembly.Figs. 1 and 2 indicate the movement of the outer die 26 against thelower assembly 2| to close the chamber 22, and Figs. 2 and 3 representsubsequent movement of the inner die 25 downward to the positionrelative to the outer die that corresponds to the desired configurationfor the blank. In the particular procedure being described, it iscontemplated that the blank 23 will be drawn progressively by stages,and to define an initial configuration for the blank the inner die 25 isinitially extended below the outer die the fluid body inthe chamber 3|is placed under pressure to cause the diaphragm 33 to press upwardagainst the central portion of the blank 23 and against the floating die38. The upward pressure of the diaphragm 35 forces the Tcentral areas ofthe blank to conform to the configurathe blank 'i'rom creeping orstretching, I substantially avoid any tendency of the material or theblank to rupture at the leading edges or along the sides of the innerdie 23. By this procedure I i am enabled to make deeper-draws thanpossible by any prevalent commercial practice. One feature to be notedhere is. that the diaphragm 33 tion of the inner die 25, one portion ofthe blank I being forced into the forming recess 21 and a minor portionof the blank being forced into the cutting recess 28. It will be notedthat the edges of the forming recess 21 are not sufllciently abrupt orsharp to sever the blank but that the walls of the cutting recess 28 aresubstantially vertical to form edges suiflciently abrupt to causerupture of the blank. As indicated in Fig. 4 the diaphragm drives asevered portion 33 01' the blank against the inner end of the recess.

The upward pressure of the diaphragm 35 also acts against the floatingdie 38 to drive the floating die upward around the inner die 21 towardthe forming surface 30 of the stationary die 26.

In the particular arrangement indicated by Figs. 1 to 'l the forming die38 is complementary to the inner die 25 with sufllcient clearance toallow for the thickness of the blank 23 and upward movement of thefloating die draws the material of the blank by forcing the blank aroundthe exposed portion of the inner die 25. The drawing action of thefloating die 38 forms a marginal flange 40 on the blank 23 and thefloating die comes to rest against the flange 40 with sufflcientpressure to iron out any wrinkles or ridges that may be formed in themarginal flange by the flange 43 disappears after the flrst stage, butany drawing operation. It is contemplated that the pressure to which thefluid body 33 will be subjected willsufllce for whatever'function,inironing out the flange of the blank is required on the part of thefloating die 38. Inone practice of the invention, about 2000 lbs. persq. in. will be employed to form metal blanks of 16 gaugejthiek- 1 nessor thicker. In another practice of the inven tion it may be desirabletodevelop 5000 lbs. pres{ sure per square inch or more.

After the blank is formed to what may be termed theinitial configurationshown inFig. 4 the pressure and volume of the fluid body 33 are reducedto permit the diaphragm 35 to withdraw to a material extent, asindicatedin Fig. 5. The operator 'then advances the inner die 25 into the chamber22 to extend the exposed surface of the inner die, as indicated in Fig.6. The volume and is formed or molded with annular corrugations 4i tofavor extensive axial flexure for deep draws.

In the procedure illustrated by Figs. 1 to '7 the metal is formed in twostages to the final conflguration shown in Fig." 7, and themarginalnumber of intermediate configurations may be contemplated withthe floating die 33 functioning to flatten out the marginal flange aftereach drawing operation. As will be explained later. provision is madefor controlling the inner die 25 and for controlling the pressure andvolume of the fluid body 33 without the necessity of opening the chamber22 so that the described cycle of forming operations may be performedexpeditiously by simply manipulating two controls.

Figs. 8 and 9 illustrate a forming procedure that is carried out by thesame apparatus with an inner die 42 substituted for the previouslydescribed inner die 23. In this second procedure. Fig. 8 corresponds toFig. 4 and the previously described steps are carried out up to thispoint of forming a blank 43 to an initial configuration. In this secondprocedure, however, the remaining steps to shape the blank to a flnalconfiguration shown in Fig. 9 are carried out without wholly releasingthe fluid body 33 from pressure. It is contemplated that the inner die42 will be progressively advanced, either continuously or intermittentlyfrom the position of Fig. 8 to the position of Fig. 9, and that pressurein the fluid body 33 will be maintained to cause the blank 43 to changeprogressively in configuration in accord with the advance of the innerdie. To carry out this procedure, it is merely necessary to have theoperating pressure efl'ective on the inner die 42 predominate over theopposing pressure exerted by the fluid body 33.

'In another practice of the invention illustrated by Figs. 10 and 11, afloating member 43 may be employed that is of substantially the sameshape as the previously described floating die 38 and. in like manner,rests on the diaphragm 35. The

' ing member 43 on top of the diaphragm 35, as

. with sufllcient force toffreezei the material of the blank to theinner die. Inother words, it is. contemplated that the pressure exertedby, the diaphrag-m willbausei the rnetal' of the blank 23 to act asarr-integral part jlo! the inner Jdi'e, there bypreventingrelativefmovementbetween the surface of the inner die-sandthesurrounding ma-f terial of the b1ank;jf; Byemploying high fluidpressure in this manner-to prevent the" material jet indicated in Fig.10, and then pressure is applied to the fluid body 33 to cause thediaphragm to carry the blank upward into intimate pressural contact withthe inner die 41'.

In some practices of my invention, especially practices involving onlyrelatively shallow draws, no floating. die will be employed to cooperatewith the diaphragm 33 Fig. 12, for'example,

shows the previously described apparatus without any floating die, theapparatus being set up with'aplain cylindrical inner die 43 to form ablank 30 to theconflguration of a shallow flanged In this practice, theblank is placed on ,thediaphragm and then pressure is applied to thediaphragm to cause the blank to envelop the exposed portion'of the innerdie 48. It will be noted that aflmarginal portion 5! of theblank isforced by the diaphragm against the flat forming surface 86 of the'outerdie 26.

Among the innumerable forming procedures contemplated in the variouspractices of my invention is a forming method exemplified by Figs. 13 md14. The setup, of the apparatus is the same as in Fig. 12 except that aninner die 62 is substituted for the inner die 48. The forming surface ofthe inner die 62 is restricted to a cylindrical surface 62 presented byan L-shaped or angular extension 66 of the inner die. The object in mindhere is to form a blank 66 to a tubular configuration represented by thecylindrical surface 68. In carrying out this procedure, the blank 66 isplaced on the diaphragm 86 as shown in Fig. 13 and then the volume andpres-- sure of the fluid body 33 are increased to cause the diaphragm tocompletely envelop the blank and the die extension 66. The blank iswrapped around the'die. extension-66: into. the form of a tube, whichtube is subsequently removed from 68 extending upward from the base anda stationary crown generally designated 66 supported by the tensionrods. The previously mentioned lower assembly 2I is stationary on thebase 51 while the previously mentioned outer die 26 of theupper assembly26 is connected with what may be termed an outer ram 6i, and the innerdie 26 of the upper assembly is carried by an inner ram 62, the two ramsbeing movably supported from the crown 66. The outer ram BI is forceddownward by fluid pressure in an annular hydraulic chamber 68 which maybe conveniently termed the outer ram lowering chamber and is retractedupward by hydraulic pressure in a pair of auxiliary lift cylinders 65.For urging the inner die 26 downward, an inner ram lowering chamber 66is provided within the stationary crown 66, and to raise the inner die asmall inner ram lift chamber 61 is provided inside the inner ram 62. Itwill .be apparent at this point that convenient control means includingsuitable control valves may be utilized to re-,- ciprocate the inner andouter dies 25 and 26 and to raise and lower the fluid pressure under thediaphragm 35. The structure of the selected embodiment of the inventionwill now be described in more specific detail.

The base 51 comprises a bed plate 68 unitary with a cylindrical pedestall6. Resting on the bed plate 68 is the lower assembly 2| which ineludes:the fluid receptacle 8i containing the body of oil 83 and having thepreviously mentioned passage 82 for communication with the body of oilthe diaphragm 35 spanning the receptacle; the clamping ring 86 removablybolted to the receptacle; the guidering l1 resting on the clamping rim;and the floating die 38 resting on the diaphragm inside the guide ring.When set up for use, the lower assembly 2| is immobilized by suitablebolts II extending downward into the bed plate 66 from peripheral lugs12- on the guide ring 81. For convenience inhandiing, both the fluidreceptacle 8| and the guide ring 31 may have peripheral knobs or handlesI8.

Each of the tenslon'rods 68 is provided at its opposite ends withreduced portions 16 carrying large retaining nuts I6. The lower ends ofthe tension rods seat in complementary bores in the bed plate 68 whilethe upper ends seat in complementary bores in a relatively thick web 11of the crown 66.

The crown 66 of the press includes the following principal parts: anouter cylinder 86 that is unitary with the web 11 and that slidinglyembraces the outer ram 6| an inner cylinder 8i that slldingly embraces.the inner ram 62 and has a' radial wall 62, the wall 82 being anchoredto the upper end of the outer cylinder by nuts 63 on studs 86: and a cap86 closing the top of the inner cylinder 8! and secured thereto by nuts61 on studs 88. v i

The outer ram 6I has a cylindrical wall 86 for sliding contact with theouter cylinder 86 and has-an-. inner radial wall 8| that slidinglyembraces the inner ram 62. The walls 86 and 8| of the outer ram 6icooperate with the outer and inner cylinders 86 and 8| and the inner ram62 to form the previously mentioned outer ram lowerin chamber 63. .Itwill be noted that this chamber 68 includes space within the crown 66above the outer ram as well as space within the outer ram below thecrown and that the cylindrical wall 860! the outer ram provides ampleclearance 62 around the inner cylinder 8| for free fluid flow betweenthese two spaces. To minimize leakage from the hydraulic chamber 68, thelower end of the outer cylinder 86 and the lower end of the outer ram 6|may each be recessed to receive suitable annular packing 93 retained bya removable metal packing ring 65. Fluid communication with the outerram lowering chamber 68 is provided by a passage 96 formed by suitablebores in the radial wall 62 at the top of the chamber.

Suitably-attached to the lower end of the outer ram 6| is what may betermed a lift ring 91 having two opposite lift arms that are attached bynuts I66 tocorresponding lift rods I6I, the lift rods being in turnconnected with lift pistons I62 in the previously mentioned liftcylinders 65. Each of the lift cylinders 65, which may be attached tothe crown 66 of the press by suitable bolts I68, is provided with a capI having a vent opening I66, and each cylinder has a lower end wall M1on which is mounted a suitable packing gland I66 surrounding thecorresponding lift rod I6I. In the course of operation, fluid flows intoand out of the lift cylinders 65 through suitable ports 6 near the lowerends of the cylinders.

Suitably connected with the outer ram 6|, for example, by attachment tothe lift ring 911s a cylindrical extension, to the lower end of which isbolted the previously'mentioned forming die 26. The cylindricalextension III may have vertical slots or windows II2 through which themovements of the inner forming die 25 may be observed. In the preferredform of my invention I provide suitable index means, such as index marksII3, on either the inner forming die or the inner ram to be read withreference to the lower end of one of the windows H2 for ascertaining theposition of the inner forming die relative to the outer forming die.

The outer forming die may comprise an outer frusto-conical steel shellH5 and an inner body II6 of some suitable alloy cast into the shell, theshell having inner ribs or flanges I I! to make the cast body unitarywith the shell. Such an inner body formed or low melting material may bereadily cast to a desired forming configuration and may be melted forrecasting whenever a design is changed or abandoned.

It is essential that the upper assembly 20 be held immovable against thelower assembly 2I during an operating cycle, especially if high fluidpressure is developed in the lower assembly. Any liquid that might beemployed for exerting pressure in the outer ram lowering chamber 63 willbe found to be slightly compressible at exceedingly high pressures andsuch contraction in the volume or the hydraulic fluid may permit theouter die 28 to retract upwardly from the guide ring 31 to a slightextent. Toprevent any upward retreat of the outer forming die, I may ofcourse employ some positive mechanical means instead or hydraulic meansfor the actuation of the outer ram 6|, but I prefer to use the hydraulicarrangement shown and to employ a suitable lock or hold-down devicewhenever exceedingly high pressures are employed.

Such a hold-down device may comprise one or more spacer members adaptedfor removable insertion between the crown 60 oi! the press and the liftring 81 of the outer ram assembly when the outer ram is at its lowerlimit position. It is contemplated that two such spacers will beprovided within convenient reach of the operator from the front. As bestshown in Fig. 15. each of these spacers may be in the form 01' aninclined bar I20 having a handle I2I, each or the bars being unitarywith a pair of spaced rings I22 rotatably embracing one of the tensionrods 58. The operator rotates the inclined bars I20 into and out ofeffective positions about the axes o1 the corresponding tension rods 58.When a bar I20 is swung outward to its ineflective position, it issupported by a collar I 23-fixedly embracing the tension rod 58.

The inner ram 62 is in the form of a closed cylinder, at the lower endof which is a tapered transverse recess I25 for dovetail engagement witha complementary upward projection I26 of the inner forming die 25. Afterthe projection I28 01' the inner forming die is inserted in the recessI25 of the inner ram, a keeper or spacer bar I21 is inserted in therecess to make the inner forming die rigid relative to the inner ram.For occasional access to the interior or the inner ram from below, theinner ram may be provided with a bottom port I28 communicating with therecess I25, the port being normally closed with a removable plug I30.

It will be noted in Fig. 15 that the inner ram lowering chamber 66 isdefined by the inner ram 62, the surrounding inner cylinder 8I of thecrown 60, and the crown cap 86. In the course of operation fluid flowsinto and out of the chamber 66 through a suitable passage I3I bored inthe radial wall 82 at the top oi! the inner cylinder 8I. prevent leakagebetween the inner ram lowering chamber 66 and the outer ram loweringchamber 68, I may provide packing assembly comprising a lower metal riI32 secured to the upper end of the inner ram 62, annular packingmaterial I33,- and an upper removable metal ring I35. Also mounted onthe upper end of the inner ram 62 is a bushing I36 carrying a packinggland I31 that slidingly embraces a fixed tube I40.

The fixed tube I40 ispart of structure that may be provided to raise theinner ram, which structure will now be described. The fixed tube I40 imounted in and extends through a bushing HI in the crown cap 83, andcarries at its upper end a hollow fitting I 42 having a lateral passageI43 tor flow or fluid into and out of the fixed tube. On the lower endor the flxed tube I40 inside the inner ram 82 is mounted a fixed pistonI45 that is slldingly embraced by a movable cylinder I46 depending fromthe upper end of the inner ram. In the particular construction shown,the movable cylinder I46 is threaded onto the lower end of the bushingI36. A suitable vent tube I41 substantially longer than the fixed tubeI40 extends upwardly axially through the fixed piston I 45, the .iixedtube I40, and a packing gland I48 0n the top of the fitting I42 toprovide communication between the atmosphere andthe interior of theinner ram below the fixed piston I45. It will be noted that the innerram lifting chamber 61 is defined by the fixed piston I45, the movablecylinder I46, and -the bushing I36 at the top of the inner ram, and itwill be further noted that the fixed tube I40 is apertured to provideone or more ports I50 for fluid flow into and out of the chamber 61.

The novel relationship in the arrangement of the outer and innercyhnders and 8|, and the outer and inner rams 6I and 62 is to be noted.The cross-sectional areas or the two rams are complementary with nointermediate gap. Only three annular seals are required: one between theinner ram and outer ram; one between the inner ram and inner cylinder;and one between the outer ram and outer cylinder.

Fig. 1'7 is a simplified vertical section of the same press combinedwith a diagram of a hydraulic arrangement that may be employed foroperating the press in one practice of the invention. A low pressurereservoir I55 for the oil or other hydraulic liquid is connected to asuitable pump I56 that supplies a high pressure tank I51, an adjustablerelief valve I58 in a by-pass I60 being provided to set the maximumpressure for the tank I51. A high pressure supply pipe I6I from the highpressure tank I51 branches to various parts or the system.

One branch I62 from the high pressure ipe I6I extends to the fluidpassage 32 o! the receptacle 3I and has a three-way control valve I63.In one extreme position of the valve I63, the high pressure tank I51 isplaced in direct communication with the receptacle 3|; in the otherlimit position of the valve the receptacle 3I is placed in communicationwith a branch I65 of a return flow pipe I66 to the low pressurereservoir I55; and at an intermediate position of the valve thereceptacle 3I is cut on from both-the high pressure pipe and the lowpressure pipe. To set the maximum pressure for the fluid body 33 in thereceptacle 3|, which pressure may be substantially below the pressure inthe tank-I51, an adjustable relief valve or pressure regulator valveI61may be provided in a by-pass I58 from the receptacle 3| around thecontrol valve I63 to the return flow pipe I65.

A pipe I10 branching from the high pressure pipe I6I to the fluidpassage 36 for the outer ram lowering chamber 63 is provided with athreeway control valve "I. At one limit position of the valve I1I liquidis permitted to flow from the high pressure tank I51 to the presschamber 63' to lower the outer ram 6|. At the opposite limit position ofthe valve, liquid is released from the chamber 63 through the valve to abranch I12 of the return flow pipe I66. At an intermediate position ofthe valve th press chamber 63 is cut oil from both the low pressurereservoir I55 and the high pressure tank I51.

To provide for lifting the outer ram 8|, the high pressure pipe I6Ileads through a three-way valve I13 to a pipe I15 that has one branchI16 to the fluid port IIO'of one of the lift cylinders 65 and a secondbranch I11 to the corresponding port of the other lift cylinder 65. Thethree-way valve-I13 likewise is movable to three positions, a position'for delivering high pressure liquid to the two lift cylinders, aposition for releasing liquid from the two lift cylinders to a branchI18 of the return flow pipe I66, and an intermediate position cuttingofl both lift cylinders from the rest of the system.

In the preferred practice of my invention the two three-way valves HIand I13 associated with movements of the outer ram 6! are operativelyconnected to a manually operable control member or handle I80, theoperative connections being indicated by dotted lines I8I. In thecontemplated arrangement, both the valves HI and I13 are at theirintermediate positions when the control member I80 is at an intermediateposition, and movement of the control member in either direction fromits intermediate position causes one of the valves HI and I13 toestablish communication between the high pressure tank I51 in the presswhile causing the other valve to establish communication between thepress and the low pressure reservoir I55. It is apparent that the outerram will become stationary whenever the control member I80 is at itsintermediate or 'neutra.l position. Movement of the control member I80from its neutral position to one of its limit positions will permitliquid to flow from the high pressure tank I51 to the outer ram loweringchamber 63 and simultaneously permit liquid to flow from the two liftcylinders 65 to the low pressure reservoir I55. Movement of the controlmember I80 from its neutral position to its alternate limit positionwill permit liquid to flow from the high pressure tank I51 to the portsIII) of the lift cylinders 65 and simultaneously permit liquid to flowfrom the press chamber 63 to the low pressure reservoir I55. Upwardmovement of the two lift pistons I02 displaces air out of the liftcylinders through the vent openings I06.

A similar valve arrangement for controlling movement of the inner ram 62includes a threeway valve I82 for lowering the inner ram, a threewayvalve I83 for raising the inner ram, and a manually operable controlmember I85 common to the two valves and operatively connected therewith,as indicated by dotted lines I86. The three-way valve I82 is in a branchI81 of the high pressure pipe I6I that leads to the fluid passage I3I atthe upper end of the press chamber 66 and a branch I88 of the returnflow pipe I66 is connected to the valve for release of fluid from thepress chamber 66. The three-way valve I83 is in a branch I90 from thehigh pressure pipe I6I that leads to the fluid port I43 at the top ofthe fixed tube. At the high pressure position of the valve I83, theliquid under high pressure passes down the fixed tube I40 and flowsthrough the ports I50 into the press chamber 61 for lifting the innerram. When the valve I83 is moved to its opposite position, liquid isreleased from the press chamber 61 through the pipe I90 to a branch I9Iof the return flow pipe I66. Movement of the control member in onedirection from its neutral position will cause the inner ram 62 to rise,and movement in the opposite direction will cause the inner ram todescend, the inner ram remaining stationary whenever the control memberis in the neutral position.

In one practice of my invention, I provide adjustable means forindividually limiting the pressures delivered to the press by each ofthe three-way control valves I1I, I13, I82, and I83. Such limiting orregulating means may comprise suitable adjustable relief valves orpressure regulator valves in bypasses across the three-way valves. Thus,in Fig. 17 I show a relief valve I92 in a by-pass I93 across thethree-way valve ill, a relief valve I95 in a by-pass I96 across thethree-way valve I13, a. relief valve I91 in a bypass I98 across thethree-way valve I82, and a relief valve 200 in a by-pass 20I across thethreeway valve I83.

The capability of the described apparatus to carry out the variousforming procedures exemplified by Figs. 1 to 14 is apparent from theforegoing description.

Starting with the apparatus in the disposition corresponding to Fig. l,for example, the operator manipulates the control I to lower the outerram 6i thereby closing down the outer forming die 26 against the guidering 31 of the lower assembly 2I. At the end of this step thedisposition of the apparatus corresponds to Fig. 2, and the operatorthen manipulates the control I to lower the inner ram 62 to extend theinner forming die 25 below the outer forming die 26 to the degree shownin Fig. 3, the operator being guided in this manpulation by the indexscale I I3. With the two upper dies thus disposed to define the initialdrawing configuration of the blank, the operator turns the valve I63 tosend high pressure liquid into the receptacle 3I to cause the diaphragmto press the blank upward as indicated in Fig. 4.

To carry out as many additional drawing stages as may be required, theoperator watches the index scale H3 and alternately manipulates thecontrol I86 with one hand and the valve I63 with the other hand. Thesucceeding drawing operations in the cycle follow each o er with solittle loss of time that very little of the heat engendered in the blankby one drawing operation is lost before the succeeding drawingoperation. Since the metal of the blank remains heated throughout theoperating cycle, relatively deep draws may be made without rupture, andthere is no necessity for annealing the metal between the succeedingdrawing operations.

In one procedure exemplified by Figs. 8 and 9, the liquid pressureupward against the diaphragm 35 is maintained at an effective valuethroughout the drawing procedure, the inner die being advanced inopposition to such pressure. One manner of carrying out such a procedureinvolves adjusting the maximum liquid pressure for lowering the innerram 62 at a sufficiently high value relative to the maximum pressure inthe receptacle 3| to cause the inner ram to advance in opposition to thediaphragm pressure. In adjusting the pressure regulating valves for suchoperation, relative areas affected by the fluid pressure must of coursebe taken into consideration. The operator first advances the inner .die42 to the position shown in Fig. 8 and then raises the fluid pressureunder the diaphragm to maximum to give the blank an initialconfiguration. While the inner die is stationary, the operator thenraises the liquid pressure in the press chamber 66 without lowering thepressure under blank; applying fiuid pressure to said fiowable means topress the blank against said forming fluctuating one of these pressuresto cause the inner die to inch" downward in opposition to pressure fromthe diaphragm. To carry out this procedure the regulating valves are soadjusted that when the pressure in the press chamber 66 and the pressurein the receptacle 3| are at normal effective values, the tendency of theram to descend is balanced by opposition from the diaphragm. When suchbalance of pressure exists, the inner ram is held stationary. The innerram may be inched downward either by intermittently raising the pressurein the chamber 88 above the normal balancing pressure or byintermittently lowering the pressure in the receptacle 3| below thenormal balancing pressure. In my preferred practice I simply oscillatethe valve I83 to cause the liquid pressure under the diaphragm tofluctuate and thereby permit the inner die to inch downward with eachfluctuation of pressure. In this procedure the transition from the blankconfiguration of Fig. 8 to the blank configuration of Fig. 9 may be madein relatively small increments in close succession. The oscillation ofthe valve I63 may be relatively slight to cause only slight drop in thepressure under the diaphragm or may be extreme to drop the receptaclepressure to minimum, but if the valve IE3 is swung to its extremerelease position, it must be quickly returned to its pressure applyingposition to prevent too great an advance of the inner die in one step.

The various operating procedures and a preferred form of my apparatusset forth herein in specific detail for the purpose of illustration andto disclose the principles involved will suggest to those skilled inthis art various changes and substitutions that do not depart from theunderlying inventive concept; I reserve the right to all suchmodifications and substitutions that come within the scope of myappended claims.

I claim as my invention:

1. A method of forming a blank to a predetermined configurationincluding the steps of: providing walls including a forming walldefining a confined space; placing said blank in said confined spacewith one side of the blank against said forming wall; providing fiowablemeans including a body of fluid in said space on the other side of saidblank; applying pressure to said body of fluid to press the blankagainst said forming wall; shifting at least a portion of said-formingwall inward toward said blank to provide a new forming configuration;reducing the volume of said fluid body to permit the blank to retreat toaccommodate said shift; and applying pressure to the body of fluid topress the blank against said forming wall after the shift.

2. A method of forming a blank to a predetermined configurationincluding the steps of: providing walls including a movable forming walldefining a confined space; placing said blank in said confined spacewith one side of the blank facing said forming wall; providing fiowablemeans in said space on the other side of said wall; applying inwardlydirected pressure to said forming wall to resist the outward pressure ofsaid fiowable means; and fluctuating one of said pressures to vary therelative magnitudes of said inward and outward pressures thereby tocause said forming wall to move intermittently to progressively approacha position corresponding to said predetermined configuration.

3. A method of forming a blank to a predetermined configurationincluding the steps of: providing walls defining a confined spaceincluding a movable forming wall and a stationary forming wall;adjusting said'movable forming wall relative to said stationary formingwall to correspond to an initial forming configuration differing fromsaid predetermined configuration; placing said blank in said space withone side of the blank facing said two forming walls; providing fiowablemeans in said space on the. other side of said blank; applying fluidpressure to said fiowable means to press th blank against said twoforming walls; applying inwardly directed pressure to said movableforming wall to substantially balance the outward pressure of saidflowable means; and fluctuating one of said pressures to intermittentlyunbalance said pressures in a direction to cause said movable formingwall to shift progressively to a position relative to said stationaryforming wall corresponding to said predetermined configuration.

4. A method of forming a blank to a predetermined configurationincluding the steps of: providing walls defining a confined spaceincluding two contiguous forming wall members corresponding tocontiguous portions of said predetermined configuration; adjusting saidtwo forming walls relative to each other to correspond to an initialforming configuration differing from said predetermined configuration;placing said blank in said space with one side of the blank facing saidtwo forming walls; providing fiowable means in said space on the otherside of said blank; providing a fioating forming wall complenrentary toone of said two forming walls intermediate said blank and said fiowablemeans; applying fiuid pressure to said fiowable means to press againstthe blank and against said-floating forming wall to force the blank intointimate contact with said two forming walls thereby to shape the blankto said initial configuration; applying inwardly directed pressure to atleast one of said two forming walls to resist the outward pressure ofsaid fiowable means; and fluctuating one of said pressures to causerelative movement of one of said two forming walls to cause the twoforming walls to progress intermittently to relative positionscorresponding to said predetermined configuration thereby to change theshape of the blank progressively to said predetermined configurationl 5.An apparatus for forming a blank to a predetermined oonflguration,including: means presenting a forming surface to one side .of the blank;a flexible sheet having one face directed toward the other side of theblank, said sheet being formed with a series of annular corrugations ofprogressively increasing diameter; a body of fiuid in contact with theother face of said fiexible sheet; and means to place said body of fiuidunder pressure to cause said flexible sheet to press said blank intointimate contact with said forming surface.

6. An apparatusfor forming ablank to a predetermined configuration,including: means presenting a forming surface to one side of the blank;walls forming a space on the other side of the blank; a body of fluid insaid space; a diaphragm spanning said space and separating said fluidfrom said blank; a floating forming member interposed between a portionof said blank and a portion of said diaphragm; and means to place saidfluid under pressure to exert pressure against said floating member andto force said blank into intimate contact with said forming surface.

7. An apparatus for forming a blank to a predetermined configuration,including: a plurality of forming members having surfaces correspond ingto portions of said predetermined configuration, said members beingpresented to one side of said blank and at least one of said membersbeing movable; walls forming a space on the other side of the blank; abody of fluid in said space; a diaphragm spanning said space andseparating said fluid fromsaid blank; a floating member interposedbetween a portion of said diaphragm and a portion of said blank, saidfloating member having a contact surface for the blank complementary toa portion of the surfaces of said plurality of forming members; a firstcontrol means operatively associated with 'at least one movable memberof said series of forming members to shift the disposition of theforming members from a disposition corresponding to an initialconfiguration for the blank to a disposition corresponding to saidpredetermined configuration; and a second control means to place saidbody of fluid under pressure to press said blank into intimate contactwith said forming members at successive dispositions of the formingmembers.

8. An apparatus for forming a blank to a predetermined configuration,including: forming means presenting a forming surface to one side of theblank; walls forming a space on the other side of the blank; 9. body offluid in said space; a diaphragm spanning said space and separating saidfluid from said blank; means to place said fluid under pressure to forcesaid blank into intimate contact with said forming surface; means toplace said forming means under pressure in opposition to said fluidpressure to urge the forming means toward said diaphragm; and means tofluctuate at least one of said pressures to cause said forming means toshift intermittently thereby to shape said blank by progressive stages.

9. An apparatus for forming a blank to a predetermined configuration,including: forming means presenting a forming surface to one side of theblank; walls forming a space on the other side of the blank; a body offluid in said space; a diaphragm spanning said space and separating saidfluid from said blank; means to place said fluid under pressure to forcesaid blank into intimate contact with said forming surface; means toplace said forming means under pressure toward said diaphragmsubstantially balancing the pressure of the body of fluid; and means tofluctuate one of said pressures to unbalance the pressuresintermittently to cause said forming means to shift intermittentlythereby to shape said blank by progressive stages.

10. An apparatus for forming a blank to a predetermined configuration,including: a plurality of forming members having surfaces correspondingto portions of said predetermined configuration, said members beingpresented to one side of ing movable; walls forming a space on the otherside of the blank; a body of fluid in said space; a diaphragm spanningsaid space and separating said fluid from said blank; a floating memberinterposed between a portion of said diaphragm and a portion of saidblank, said floating member having a contact surface for the blankcomplementary to a portion of the surfaces of said plurality of formingmembers; means to place said body of fluid under pressure to exertpressure on said floating member to press said blank into intimatecontact with said forming members; means to place at least one movablemember of said plurality of forming members under pressure tosubstantially balance the pressure of said body of fluid; and means toupset the balance of said pressures intermittently to cause at leastsaid one movable member of said plurality of forming members to shiftthe relative dispositions of the forming members intermittently andprogressively from dispositions corresponding to an initialconfiguration for the blank to relative dispositions corresponding tosaid predetermined configuration thereby to cause the blank to be shapedprogressively in stages,

11, An apparatus for forming a blank to a predetermined conflguration,including: a movable male die presenting a drawing surface; an adia centstationary die presenting a stationary forming surface; means to advancethe male die against the blank; hydraulic means to press a progressivelyincreasing portion of the blank into intimate contact with the advancingmale die with suflicient force to freeze said portion to the male dietherebyto prevent rupture of the blank; and a die complementary to saidstationary die to press adjacent portions of said blank against saidstationary die.

12. An apparatus for forming a blank to a predetermined conflguration,including: a movable male die presenting a drawing surface; asurrounding stationary die presenting a stationary forming surface;means to advance the male die intermittently against a portion of saidblank; hydraulic means to press the blank into intimate contact with theadvancing male dieto prevent rupture of the blank; and variable means topress marginal portions of said blank against said stationary die duringpauses in the advancement of the male die.

13. An apparatus for forming a blank to a predetermined configuration,including: a receptacle adapted to receive said blank in its entirety;an inner die and a surrounding outer die cooperating to form a cover toclose said receptacle, said inner die being movable to various positionsrelative to said outer die to change said cover to various formingconfigurations; control means movably supporting said inner die; indexmeans to indicate the position of said inner die relative to said outerdie; a body of fluid in said receptacle;

and means to place said body of fluid under said blank and at least oneof said members bepressure to force said blank against said inner andouter dies.

14. An apparatus for forming a blank to a predetermined conflguration,including: a plurality of contiguous forming members adapted forrelative movement while still contiguous from a disposition providing aninitial forming configuration to a predetermined disposition providingsaid predetermined configuration; means cooperating with said pluralityof forming members to form a chamber completely enclosing said blankwith one side of the blank facing said forming members; flowable meansincluding a body of fluid progressively forming the blank to saidpredetermined configuration.

15, A method of forming a blank through a progressive series ofintermediate configurations of the blank as a whole to a predeterminedconfiguration of the blank as a whole, including the steps of: providingcontiguous forms relatively movable through a progressive series ofdispositions to present contiguous forming surfaces conforming to saidintermediate and predetermined configurations of the blank as a whole;disposing said forms in initial positions for such progressive relativemovement; completely enclosing said blank in a position with one side ofthe blank facing said forms; enclosing fiowable means including a bodyof fluid on the other side of said blank; causing relative progressivemovement of said forms from said initial disposition to the dispositionconforming to said predetermined configuration; and applying pressure tosaid body of fluid to force said blank into intimate contact with saidcontiguous surfaces to cause the configuration of the blank to followthe changes in disposition of the forms.

16. A method of forming a blank through a progressive series ofintermediate configurations of the blank as a whole to a predeterminedconfiguration of the blank as a whole, including the steps of: providingforms relatively movable through a progressive series of dispositionsconforming to said intermediate and predetermined configurations of theblank as a whole; completely enclosing said blank in a position with oneside of the blank facing said forms; enclosing fiowable means includinga body of liquid on the other side of said blank; causing relativemovement by stages of said forms from an initial disposition to a finaldisposition providing said predetermined configuration; applyingpressure to said body of fluid to force said blank against said forms;and reducing said pressure during each stage of relative movement ofsaid forms toward said final disposition. v

17. A method of forming a blank through a progressive series ofintermediate configurations to a predetermined configuration, includingthe steps of: providing a plurality of forms relatively movable througha progressive series of dispositions conforming to said intermediate andpredetermined configurations; disposing said forms in initial positionsic! such progressive relative movement; placing said blank in aposition with one side of the blank facing said forms: placing an innerform on the other side of said blank opposite one of said plurality offorms; placing fiowable means including a body of fluid on said otherside of said blank and against the inner side of said inner form;causing relative progressive movement of said plurality of forms fromsaid initial disposition to the disposition conforming to saidpredetermined configuration; and applying pressure to said body of fluidto force said inner form against said blank and force the blank againstsaid plurality of forms thereby to cause the configuration of the blankto follow the changes in disposition of said plurality of forms.

18. Al method of forming a blank through a progressive series ofintermediate configurations to a predetermined configuration, includingthe steps of providing a plurality of forms relatively movable through aprogressive series of dispositions conforming to said intermediate andpredetermined configurations; placing said blank in a position with oneside of the blank facing said forms; placing an inner form on the otherside of said blank opposite one of said plurality of forms; placingfiowable means including a body of fluid on said other side of saidblank and against the inner side of said inner form; causing relativemovement by stages of said forms from an-initial disposition to a finaldisposition conforming to said predetermined configuration; applyingpressure to said body of liquid to force said inner form against saidblank and force the -bers being adapted for relative movement forvarying presentation of said surfaces to define a varying formingconfiguration; means for causing relative movement of said formingmembers from a first disposition in which the presented portions of saidsurfaces correspond to a first configuration of said blank to a seconddisposition of said forming members in which the presented portions ofsaid surfaces correspond to said predetermined configuration; areceptacle containing a body of fluid; a flexible member comprising onewall of said receptacle disposed for movement to press the blank againstsaid forming members; and means to place said body of fluid underpressure at successive relative dispositions of said forming members.

20. An apparatus for forming a blank to a predetermined configuration,including: a plurality of wall members defining a chamber, one side ofsaid chamber presenting a forming surface, at least one of said wallmembers on one side of said chamber being relatively movable toward andaway from the opposite side of the chamber for varying the configurationof said forming surface; a fiexible sheet spanning said chamber betweensaid two sides of the chamber in a position for movement toward and awayfrom said one side of the chamber to force said blank against saidforming surface; means to cause relative movement between said wallmembers to vary the configuration of said forming surface; and means toapply fluid pressure to said flexible member to press said blank intointimate contact with said forming surface to shape the blank tosuccessive configurations of the forming surface.

21. An apparatus for forming a blank to a predetermined configuration,including: die means; means cooperating with said die means to form achamber completely enclosing said blank with one side of the blankfacing said die means, said die means being movable toward said blankfrom a position at which the surface of said die means together with theadjacent surface of said cooperating means forms a combined formingsurface of an initial configuration to an advanced position at which thesurface of said die means together with the adjacent surface of saidcooperating means forms a combined forming surface 01! saidpredetermined conflgurato move said die means inward in opposition totion; iiowable means including a body of fluid in said sustainedpressure to form said blank prosaid chamber 'on the other side of saidblank; gressively in said predetermined configuration; means 'zto' placesaid body 01' fluid under sus-' and means to release fluid from saidchamber distsined pressure .to force said blank into intimate 6 placedby said inward movement or the die means contactwith said combinedforming surface-sat without releasing said pressure.

the diluent posiitons of said die means, means HENRY COLLIER SMITH, JR.

